Screen assembly for grinding mills



Oct. 3 1933. o. N. cam-:DELL

SCREEN ASSEMBLY FOR GRINDING MILLS Filed Sept. 4. 1931 2 Sheets-Sheet l aff.

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U uuml A TTORN E Y.

Oct. 3, 1933. o. N. GREDELL 1,928,837

SCREEN ASSEMBLY FOR GRINDING MILLS Filed Sept. 4, 1951 2 Sheets-Sheet 2 aoaocovn DOOPO OOOOQYIDOO JNVENTOR. 0270 A( rea/a 3mm/ft A TTORNE Y.

Patented oct. 3, 1933 UNITED STATES PATENT OFFICE SCREEN ASSEMBLY FOR GRINDING MILLS Otto N. Gredell, Kansas City. Mo., assignor to' Standard Steel Works, North Kansas Mo., a corporation of Missouri City,

Application september 4,1931. seria1N0.561,173

18 Claims.

are securely anchored in position to co-operateV with the grinding elements of the mills.

It is also an object of the invention to provide for ready removal and application of the screens when it is desired to substitute screens of different mesh in order to grind all of the various kinds of commodities encountered in custom grinding.

In accomplishing these and other objects of the invention I have provided improved details of structure, the preferred form of which is illustrated in the accompanying drawings wherein:

Fig. 1 is a vertical elevational View partly in 20 section of a grinder equipped with a screen embodying my invention.

Fig. 2 is a fragmentary detail perspective view of a portion of the grinder illustrating the clamping members for securing the screen.

Fig. 3 is a detail sectional view on the line 3 3 of Fig. 2 particularly illustrating mounting of the screen in the grinder casing. Y

Fig. 4 is a sectional view through the casing and sealing elements at the upper end of the screen on the line 4 4 of Fig. 2, and p Fig. 5 is a similar view through the sealing elements at the opposite end of the screen.

Referring more in detail to the drawings:

1 designates a grinder casing including vertical side plates 2 and 3 spaced apart by a substantially circular band 4 to form a cylindrical rotor chamber 5. The ends 6 and 7 of the band terminate short of each other to provide a radial discharge outlet 8 opening to an exhaust chamber 9. The exhaust chamber 9 is defined by upward extending portions of the side plates and'by spaced plates 10 and l1 having the width of the band 4. The plate 10 extends vertically between the side plates at a point spaced from a vertical tangent to the circular band and its lower end is bent inwardly at an angle to terminate in a footing flange 12 which seats on the projecting fiange of an angle member 13. The angle member is fixed across the Width ofthe band at a` point spaced below its terminal edge to form a screen engaging ledge 14 for a screen later described. Y

The other plate 11 has its upper end co-operating with the upper end 'of the plate l0 to form a neck 15 to secure an'exhaust conduit 16 and its lower end inclines downwardly to rest on the band 4 at a point spaced from its end 6. The end of the band thus forms a ledge 17 complementary to the ledge 14 previously described.

The bandv4 including the plates 10 and 11 are clamped in position between the side plates by bolts 18, certain of the bolts extending through triangle shaped loops 19 welded to said members as shown in Fig. 1.

Rotatably mounted within the rotorv chamberY is a shaft 20 carrying a rotor disk 21 having a plurality of pivotally' mounted Yhammers 22 and radial cutter blades 23 that co-operate with a xed cutter blade 24 mounted adjacent a feed inlet opening 25. The specific construction of the rotor, however. forms no part of the present invention.

The outer edges of the hammers move through a path in close proximity with the inner surface of the band 4 to co-operate therewith in reducing material drawn into the chamber through the inlet opening 25 formed in one of the side plates 2 or 3. The hammers also serve to create a fan blast fordischarging reduced material through the discharge outlet vand through the exhaust conduit 16.

In order that the material may be retained within the grinding zone until it has become reduced to the proper size the discharge outlet is closed by a screen 26 having a mesh or apertures 27 proportionate to the desired degree of flneness to which the material is to be ground.

It is important that the screen be secured tightly within the casing since the impacts caused by the centrifugally revolving mass will cause the screen to bulge outwardly and become displaced. It is also important that the screens be mounted for quickV change when changing from one type of material to another sov that the machine is adaptable to custom grinding as now described. l

The side plates 2 and 3 are provided with arcuate slots 28 and 29 respectively extending between the lower ends of the plates 10 and 11 so that an arcuate shaped screen may be inserted therethrough to permit its ends to rest against the ledges 14 and 17 and substantially form a continuation of the band 4 bridging its gap.

Fixed to the side plates 2 and 3 exteriorly thereof are arcuate shaped angle members 30 and 3l having laterally projectinganges 32 and 33 positioned with their upperV faces aligning with Vthe inner arcuate edges of the slots 28 and 29 to form ledges 34 and 35 to support projecting side edges 36 and 37 of the screen 26 as shown in Fig. 3.

The lower ends of the angle members extend beyond the lower ends of the slots while their upper ends may align with the slots to accommodate sealing blocks 38 and 39 at the upper and lower ends respectively.

The upper sealing blocks are preferably formed of rectangular blocks of rubber substantially the Width of theledges and are slidably mounted in socket members 40 welded to the side plates adjacent the upper ends of the angle members, the blocks being seated on springs 41 which tend to lift them from the sockets to seal against the upper ends of clamping strips 421and'43.V

The lower blocks 39 are slightly wider than ythe width of the clamping strips Vand are securedto the ledges by rivets or the like, so that the mdsof the clamping strips may abut'thereagainst for sealing the space formed betonen 'the clamping strips and the flanges of the angle members.

The clamping strips are to extend over the outer surface of ytheprojecting sides of -thescreen and arepreferably-formed-of a. Z-bar bent into an arcuate shape-similar to the curvature of the screenlwhereby :the'flanges 44 -thereof'lie against f the outer :faces of' the side-plates and form closures vforfthe arcuate .slots 28 and.29 and the fianges 45 overlap-the eide edges of the screen.

.The flanges 45 falso overlap thel projecting flanges 32 and 33 of the angle members 30 and 31,

. lwhilethe intermediatehorizontal portion 46 lies flat on the' screen.

Inorder-to sealthe side edges-of fthe screen to co-operate with Athe sealing-blocks in preventing leakage of'air through the slots, .theinner faces s 'of the flanges 45 are proyided with rubber or like f stripsV 4 7 which are` preferably riveted vto the flanges 45 of the clamping strips and the lower ends thereof abut-againstthe blocks 3 while the upper-endsoverlap the vsealing blocks 38 to effect seals therewith.

IIt is thus apparent thatthe vhorizontal portions 46vof-the clamping strips lie fiat on the projecting sides 36 and-37 of thescreen whilethe screen Alies fiat against the ledges 34 and 35Cand vthe screen ls yretained thereby-at a Afxediiistance from the ends of the hammer, but the clamping strips-may be shifted laterally toward the sidesl of the casing to compress the sealing strips 4dr-against',l the edges of-theanges 32 and 33, effecting tight seals and preventing/escape of air.

In order-to retainhthe clamping strips in position, I provide clamping lugs 48 located at intervals `along the .lengthl thereof. The clamping lugsare preferably providedfwithbody portions 449having fiatseats-50 to engage -thehorizontal portions -of thek clamping strips.v and having tongues 51 whichfproject upwardly4 therefrom Ato engage inloops52. The body portions ofthe lugs arealso provided .with downwardly inclinedarms 53 having notches 54-to admit bolts 55 carried-by anchoring members 56.

Thek loops 52-are spaced radially vfrom the-slots 28 vand .29 and are'preferably welded tothe side plates 2` and 3.

" l The anehoringmembers are clipshaving ends der .the clips, are extended .through the slotted ends 58 and through 'the notches-54 in the lugs and are provided with wing nuts 60 whereby the .arms of the lugs may'bedrawn towards the casing, which tilting of the lugs causes the body portions thereof to engage in the angle formed by the portions 44 and 46 of the clamping strips to draw the strips down tightly against the screen and at the same time against the sides` of the casing to lclose the slots. This clamping move ment of the clamping strips also draws the rubber strips tightly against theedges of the arcuate ledge members for effecting aseal to exclude air from blowing through the slots.

Assuming that a screen has been assembled in the grinder and it is desired to change the screen for one of different mesh, the wing nuts 60 are loosened to allow Ethe `bolts to drop from the notches 54 in the lugs 48. The lugs 48 are then free Ato be removed after which the clamping strips 42 and 43 are lifted from the screen. The screen may then be slid sidewise through either of the Yslots 28 or 29 and withdrawn. A screen l having the proper size apertures may then be slid edgewise through one of the slots until both ofV its edges project equally 'from the sides of the casing and lie on the ledges34 and 35. The clamping strips 42 and 43 are `then applied over the projecting portions of the screen vwith the flanges 44 closing the unused portions of the-slots and the flanges 45 engaging and overlapping the flange ofthe angle members 30 and 31.

The lugs 48 are applied with the tongues 51 engaging in the loops .52 andthe body portions 49 seated within the angles of ltheclamping strips formed between the portions '44 and 46 thereof,

. after which the bolts 55 are swung into the notches 54. VThe wingnuts are then tightened against the arms 53 to draw the clamping strips into clampingl position.

Thescreen is thusvheld rigid because both side .edges thereof are clamped throughout their entirelength and its ends are 'drawn against the 'ledges 14 and 17. With the screen thus anchored there is verylittle possibility of its buckling or .moving out of position due to :the violent impacts produced in the grinding operation. It is also impossibley for the reduced material to escape around the edges of the screen. "The reduced materialfisgtherefore, all forcedthrough the apertures-"of the Iscreen to obtain a uniform Areduction of the comminuted-material.

.Itis also apparent that dueto the seals effected Abythe sealingmembers it is impossible for the air generated by the rotorto'escape through the screenslots.

What I claim andfdesire to Vsecure by Letters Patent is:

' .f In a grinding mill'of the character described,

Aa rotor casing including sidewalls having slotted openings therethrough, ledge members'xed to said side walls adjacent said openings, a screen Vmember in thel casing having side edges resting directly on said ledge members, clamping strips covering the slotted openings, resilient strips carried by "theclamping strips and engaging the edges of the screen to effect a seal, and clamp members for securing the clamping strips in clamping Contact with the screen and the resilient strips against the 'screen and ledge members.

2. Ina grindingmill of the character described,

' a rotor casing including side walls having slotted openings, ledge members fixed to said side walls kadjacent said openings, a screen member in the casing having side edges resting directly on said ledge members, clamping strips engaging the op- .posite face of the screen, sealingY means associated with the clamping strips and engaging side edges icc of the screen, and means for anchoring said clamping strips in Lengaging position with the screen and withsaid sealing means.

tothe casing-adjacent said slots, ascreen member in the casing having side vedges projecting through said slots and resting on the ledge members, arcuate clamping strips associated with theV .ledge members to retain the edges of the screen therebetween, loops fixed to the casing at one sideof -the slots, bolt anchoring means aligned lugs engaging the loops and the bearing on. the

-clamping strips, and bolts carried by saidV anchor.-

ing means for securing :the lugs. q

4. In a grinding mill of the character described,

a rotor casing including side walls having aligning arcuate slots, arcuate ledge members von the casing adjacent saidslots, a screen member in the casing having side edges projecting through said slots and resting on the ledge members, an arcuate clamping strip associated with the ledge members to retain the edges of thescreen therebetween, loops flxed'to the casingat oneside-of the slots, bolt anchoring means aligned, with the loops at the opposite sides of the slots,` lugs lbearing on the clamping strips, tongues on the :lugs engaging the loops, arms projecting fromthe `lugs laterally of the clamping strips. and bolts extending through the arms, and the anchoring means toV secure the lugs in clamping engagement with the clamping strips. Y A Y 5. In a grinding mill of the character described,a\rotor casing including side walls having aligning arcuate slots, arcuate ledge members xedvto Uthe casing adjacent said slots, a screen member inthe casing having side edges projecting through said slots and resting on the ledge.

members, anv arcuate clamping strip associated with the ledge members to retain the edges of the screen therebetween, flexible sealing-strips associated with' the `clamping strips to eiect a seal with the edges of the ledge members, and yielding sealing members at the ends ofv said ledge members to effect a seal with the ends of the clamping strips.

6. In a grinding mill, a rotor casing including side walls-having arcuate slots, a band member `cooperating with the side walls to form a rotor chamber and having its ends terminating adjacent the ends of said slots to form a discharge outlet, an arcuate screen member insertable through said slots and having its ends resting on the ends of said band member to cover said disdischarge outlet, an arcuate screen member covmembers in position.

8. In at grinding mill, 4a casing including side walls having aligning arcuate slots, a circular 3. In a grinding mill of the characterdescribed, a rotor casing including sidewalls having` align ving arcuate slots, arcuate ledge membersfxed band member' cooperating VwithY said walls to form a grinding chamber 'and having its ends terminating adjacent theends of said slot to 1 form a discharge outlet, an arcuate'zscreenrmember covering the. discharge outlet and having its ends engaging the ends of` said band member and its sidesprojecting through said slots, ledge memc bers supportingV the projecting edges of said screen, Aarcuate clamping members associated rwith the ledge members to retain the edges of with the loops at the opposite sides of the slots;v

the screen'` therebetween-loops xed to the side vwalls at one side ofVV said slots, bolt-anchoring means aligned with the Vlo'ops at the opposite sides of the slots, lug members engaging the loops and engaging the'clampng members, and bolts engaging said` anchoring means and the lugmem- ,bers forretaining said clamping strips.

forma discharge outlet, an arcuate screen member covering the-discharge outlet and having its ends engaging the ends of said band member and its sides projecting through said slots, ledge members supporting the projecting edges of said screen, arcuate clamping 'members associated with the ledge members to retain the edges of the screen therebetween, lug members engaging the clampingmembers, and means on the side walls at opposite sides of said slots for anchoring said lug members.`

10. In a grinding mill of the character described. a casing, ledge members xed to the casing, clamp members associated with the ledge members, a screen having its edgesv engaged between the-hledge members and the clamp members, andresilient means engagingV the edges of the screen and the ledge members for sealing the screen with said members. v

11-. In a grinding 'mill, a rotor casing including spaced side walls and having an arcuateshaped opening in one of said side walls, arcuately arranged-screen supports on the side walls, an arcuate-shaped Y screen insertable through said opening to engage said supports, an arcuate-shaped member covering said opening and directly engaging the face of the screen directly above said support adjacent the opening, a compressible strip positioned between the arcuate-shaped member and a side edge of the screen to prevent leakage of material from the grinding mill, and means engageable with the casing for clamping the arcuate member against the screen and the screen against said support in position over'said opening.

12. In a grinding mill, a rotor casing including spaced side walls and having an arcuate-shaped opening in one of said side walls, arcuately arranged screen supports on the side walls, an arcuate-shaped screen insertable through said opening to engage said supports, an arcuateshaped member covering said opening and engaging the screen on the side opposite said supports, a compressible strip positioned between the arcuate-shaped member and an edge of the screen to prevent leakage of material from the grinding mill, clamping members engageable with the casing and having a portion engaged with the arcuate-shaped member, and clamping bolts extending through said clamping members tighten the arcuate member against the adjacent screen `terminating adjacent the ends -of said slot to support and. the ycompresslble strip.. fagainst'the edge-oi the screen.

13. In a .grinding mill,a casinginclnding a. side wall having an arcuateL slot,xarcuately arranged screen supports on the Ycasing inalignment with'said slot, :anarcuate screen member insertable throughsaid slot, an arcuate clamp#I ing member associated with" one ofsaid supports to retain the `edge of thescreen' therebetween, loops fixedl Vto saidz side wall'at. one sidexof the slot,boltanchoring means aligned withthe loops at opposite sides oi'the slot, lug members en'-y gaging the clamping member and 'having arms engaging the loops and :arms extending out-4 wardly yfrom .the clamping member, and bolts engaging said .anchoring means andther extending arms of the. .lugmembers for securing the clamping strip yagainstrthe screen and the screen against the support to preventradial movement of the screen.

14. In a grinding Imill `Aof the character de-V scribed, a rotor casing including a side wall .hav--v ing an arcuate slot,. arcuately arranged ledge members fixed Vto the casing 4.adjaaicent said slot,

Ya screen member 'in the casing havingits edges resting on said ledge members'Y and projecting through said slot, an arcuate clamping strip associated Awith the ledge member adjacent saidopposite laces directly engaged bythe clamp members, and a yielding sealing material engagngfthe side edgesof the screen and the Vledge members to effect a sealy with the ledge-members.

, 16.-A grinding'fmill offthecharacter de- Y scribed, arotor caslngin'cluding side'wallshavlng arcuate slots, ledge: members vnxedto the side Walls in alignment with edges of 'the"slots, an arcuate screen member extending through the slots and having-.side edges restingontheledge aroate clamping :strips having kflange portions direcyrengaglngithe screenabove the ledge :members and. having. .Elaterally extending flanges overlappingsidezedgesof the ledge members; sealing strips. between5 theV lateral .flanges and the .fledge.members`, and meansior clamping theclal'nping the/strips tolthe ledge-members to retain .the edges. ofthe vscreentl'iereaga'inst and ltlre'ssea'lingrstrivpszin sealing relation with the ledge memberszandyslde `edges.of..tlfie screen.

`1'7. Inl afg'rrnding mill o! the character described, av rotor casing 4including side :walls :having arcuate slots', ledge members fixed to the side walls in alignment Awith edges of theslots,

anrarcuate screen-.member extending through vthe slots and having side :edges: yresting yon the ledge.members, arcuate clamping strips `having horizontal .portions .engaging the screen vabove the ledge`-members, -lateral .flanges extending from opposite edges-,of the horizontall portions forclosing said slots and overlapping side edges of vthe ledge members, vsealingstrips between :the

ledge wand .the overlapping lateral flanges, .and dl'neans for. clamping the 'clamping strips .to .the ledge membersto retain edgesof thev screen thereagainstand theA sealing strip in sealing contact'withthe ledge :members and l'the edges'of the screen.

A18.1 In a 'grinding mill oi' .the character 5descrlb'ed', a rotory casing .including a side wall having an arcuateV slot, ledge members lixed to che casing .in alignment with ani arcuate edge .of the slot, an arcuate screen member extending Vthrough said slot'and having side edges lresting yon'the ledge members; an arcuatetclampingstrip having ahorizontal yportion directly engaging the screen .member extending through rsaid slot and having `oppositely directed vlateral iianges on opposite sides 'of vthe `horiaontal portion yfor closing said slot and overlapping 'the edge of said-ledge member, a sealing strip between the edge-of `rthe ledgememberand the overlapping flange to sealing-ly engage the edge of the screen, and means for .clamping the clamping strip 'tothe ledge lmember Atoretain the screen thei'eagainst` and the ysealing'strip in sealing contact `with the ledge memberand the edge of the screen. 

